1. Field of the Invention
The present invention relates to an optical recording medium, and more particularly, to a recording/reproducing method of a rewritable optical recording medium.
2. Background of the Invention
In general, there are rewritable compact disc, and rewritable digital versatile disc (DVD-RW, DVD-RAM, DVD+RW) in optical recording mediums, particularly, in optical disks, which are rewritable freely and repetitively. In those rewritable optical disks, information writing /reading thereto/therefrom are made repetitively. As the nature of use of the optical disk is, the repetitive write/read of information causes a change of a mixing ratio of a recording layer mixture provided for recording the information from an initial mixing ratio, which leads to a loss of initial properties of the mixture that causes an error in writing/reading information, which is called degradation. Areas of the degradation are turned up as defective areas when formatting, or write or read command for the optical disk is carried out. Other than the degradation, defective areas on the rewritable optical disk are caused by scratches on a surface, dusts, and/or from production defects. Therefore, in order to prevent writing/reading data to/from the defective areas formed by the foregoing causes, management of the defective areas is required. To do this, as shown in FIG. 1, DMAs (Defect Management Areas) are provided in lead-in areas and in lead-out areas of the optical recording medium for managing the defective areas on the optical recording medium. And, data areas are managed in zones (or groups), each having a user area for use in actual writing of data and a spare area for use in a case of defect occurrence in the user area.
In general, there are four DMAs provided in one disk (for example, a DVD-RAM), two in the lead-in area and the other two in the lead-out area. As management of the DMAs is important, the same data is repeatedly written in the four DMAs for protection of data. Each DMA has two blocks having 32 sectors in total, i.e., one block has 16 sectors. A first block of each DMA (called as DDS/PDL block) includes a DDS (Disk Definition Structure) and a PDL (Primary Defect List), and a second block (called as SDL block) of each DMA includes an SDL (Secondary Defect List). The PDL is a primary defective data storage portion and the SDL is a secondary defective data storage portion. In general, the PDL is a storage of entries of all defective sectors identified in formatting, i.e., initializing and re-initializing, of the disk. Each entry has an entry type and a sector number corresponding to a defective sector. On the other hand, the SDL, listed in block units, is a storage of entries of defective areas occurred after the formatting, or defective areas which can not be stored in the PDL during the formatting.
As shown in FIG. 2, each SDL entry has an area in storage of a sector number of a first sector in a block having a defective sector occurred therein and the other area in storage of a sector number of a first sector in a spare block which will replace the defective block. And, one bit is assigned to each entry for FRM (Forced Reassignment Marking); if the one bit is 0b, it indicates that a spare block is assigned and the spare block has no defects, but if the bit is 1b, it indicates that no spare block is assigned, or an assigned spare block is defective. The defective areas (i.e., defective sectors or defective blocks) in the data area are replaced with good areas, according to a slipping replacement algorithm or linear replacement algorithm.
Referring to FIG. 3A, in the slipping replacement which is applicable to a case when a defective area is listed on the PDL, if the defective sector listed on the PDL is present in the user area on which an actual data is to be written, the defective sector is skipped, and instead, the defective sector is replaced with a good sector next to the defective sector in writing a data. Consequently, the user area on which the data is being written is pushed backward, to occupy the spare area as much as the skipped defective sector, at the end. That is, the spare area is assigned to the user area as much as the skipped defective sectors. For example, if there are two defective sectors listed on the PDL, the data is written pushed back by two sectors into the spare area.
And, referring to FIG. 3B, in the linear replacement which is applicable to a case when a defective area is listed on the SDL, if there is a defective block listed on the SDL, the defective block is replaced with block units of replacement areas assigned to the spare area in writing the data. Though a PSN (Physical Sector Number) assigned to the defective block is not changed, an LSN (Logical Sector Number) is transferred to the replacement block, together with the data. This linear replacement is effective in non-realtime writing/reading a data.
FIG. 4 illustrates a block diagram showing one example of a recording portion in a related art optical recording/reproduction device provided with an optical pickup for writing/reading a data to/from an optical recording medium, a pickup mover for moving the optical pickup, a data processor for processing and providing an input data to the optical pickup or processing a data read or received from the optical disk through the optical pickup, an interface, and a microcomputer for controlling the above units. A host is connected to the interface of the device for recording/reproducing a data to/from an optical recording medium for exchange of command and data.
Referring to FIG. 4, when a data to be written is provided to the host, the host provides a write command to the device for recording/reproducing a data to/from an optical recording medium, together with the data to be written. Upon reception of the data to be written on the optical recording medium, the recording/reproducing device writes the data starting from a position designated by the write command. In this instance, the recording/reproducing device writes no data on defective areas utilizing the PDL and the SDL which indicate defects on the optical recording medium. That is, physical sectors listed on the PDL are skipped in the writing, and, as shown in FIG. 5A, physical blocks sb1kA and sb1kB listed on the SDL are replaced with replacement blocks sb1kD and sb1kF assigned to the spare area in the writing. In this instance, as shown in FIG. 5B, (0, sb1kA, sb1kF) and (0, sb1kb, sb1kD) are left on the SDL entry. The (0, sb1kA, sb1kF) indicates that a spare block without defects is assigned and a data to be written on a defective block sb1kA in a user area is written on a replacement block sb1kF in a spare area. And, in the writing or reading, if a defective block not listed on the SDL, or a block with a high possibility of error occurrence is present, the block is taken as a defective block, a replacement block is located in the spare area, data of the defective block is written again in the replacement block, and a first sector number of the defective block and a first sector number of the replacement block are listed in association with each other on the SDL entry.
In this instance, in order to write data while replacing the defective block listed on the SDL with a replacement block assigned to the spare area, the optical pickup must be shifted to the spare area and returned back to the user area again. However, a time period required for the shifting and returning back is a great obstacle for realtime writing. Accordingly, different methods for managing a defective area applicable to the case when a realtime writing is required, such as A/V (for example, movies), are suggested. One of the methods is the skipping method in which no linear replacement is employed in using the SDL, but a data is written on a good block next to an encountered defective block as shown in FIG. 6. In the skipping method, not only the defective block listed on the SDL, but also a new defective block not listed on the SDL (a hatched block in FIG. 6) are skipped. By doing so, the obstacle in a realtime writing can be eliminated because the optical pickup is not required to shift to the spare area every time the optical pickup encounters a defective block. This reduces a shifting time of the optical pickup.
However, the skipping method may cause some problems in the realtime writing and reading. That is, data writing is, in general, proceeded in block units each having 16 sectors, a block unit of ECC (Error Correction Code). As shown in FIG. 7A, each sector has a header field, a mirror field, and a recording field, and, as shown in FIG. 7B, the header field in turn has four header fields (header 1 fieldxcx9cheader 4 field). And, as shown in FIG. 7C, each header field in FIG. 7B has an area representing sector information and an area representing a sector number, and the sector information area in turn has areas of a PID (Physical Identification) representing a sector address, a sector type and a layer number. That is, one sector has four PIDs in total. In this instance, if there are PID errors more than a preset number assigned for one sector, such as 3, the sector is taken as a defective sector. If there is one or more than one defective sectors each having such PID errors in one ECC block, the block is taken as a defective block.
As shown in FIG. 7A, the recording field includes a data field for recording data which are called data unit 1, data unit 2 and data unit 3 according to signal processing steps. The data unit 1 is a data processed until an ECC encoding, the data unit 2 is a data ECC encoded, and the data unit 3 is a data modulated from the data unit 2 for actual writing. If a defective block listed on an SDL or a sector having a PID error is encountered during writing a realtime data, the block containing the sector is taken as a defective block and is skipped to a next good block, when LSN should be increased as many as a number of the skipped blocks for subjecting the data to be written to an ECC encoding again using the increased LSN. And, as the host writes the data not at a designated position, but at a new position, the host should identify information on the defective block and change file information. To do this, the optical disk recording/reproducing device should transfer the information on the defective blocks to the host, and the host should update the present record of information (for example, file system, and the like) according to the information on the defective block.
And, the optical disk recording/reproducing device should finish the ECC encoding and modulation before the pickup reaches the next good block, which fails in some cases. That is, although the pickup exists on a good block, the pickup can not write data on the good block if ECC encoding and modulation of the data to be written are not finished, yet. Therefore, in order to write data on the good block, the pickup should jump back one track after the disk makes one further turn, which time period can be an obstacle for a realtime writing. And, the addition of a control circuit for conducting the ECC encoding and modulation of transferred data again in skipping the defective block for writing the data on the good block requires a complicated hardware. The return of the error information from the optical disk recording/reproducing device to the host required for skipping the defective block because no data can be written/read to/from the defective block, makes an interface between the optical disk recording/reproducing device and the host complicated and gives a burden to the host. That is, since the optical disk recording/reproducing device should communicate the skipped defective block information to the host and the host should update an existing information (for example, file information, and the like) according to the information on defects, the interface is complicated and burden on the host is increased in the related art.
Accordingly, the present invention is directed to a recording/reproducing method of an optical recording medium that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the method for recording/reproducing a data to/from a rewritable optical recording medium, includes the steps of (1) conducting data writing/reading to/from a defective block if the defective block is encountered during a realtime writing/reading, and (2) conducting data writing/reading to/from a replacement block of the defective block if the defective block is encountered during a non-realtime writing/reading.
The above method further includes the step of storing positional information of the defective block if the defective block is a new defective block.
The positional information of the defective block is preferably stored in an SDL (secondary defect list).
If the defective block is encountered during the realtime writing/reading, only the positional information of the defective block is stored in the SDL, including information that no replacement operation is made.
If the defective block is encountered during the non-realtime writing/reading, positional information both of the defective block and the replacement block is stored in the SDL, including information that replacement operation is made.
In the realtime writing/reading, data reading is started from the defective block in reading after completion of writing.
In other aspect of the present invention, there is provided a method for recording/reproducing a data to/from an optical recording medium in realtime, including the steps of (1) conducting a data writing/reading to/from a defective block as it is if the defective block is encountered during data writing/reading, and (2) storing positional information of the defective block if the defective block is a new defective block.
In another aspect of the present invention, there is provided a method for recording/reproducing a data to/from an optical recording medium in realtime, including the steps of (1) determining whether a defective block is one listed on the SDL if the defective block is encountered during data writing/reading, (2) continuing the data writing/reading on the defective block as it is if it is determined in the step (1) that the defective block is one not listed on the SDL, and (3) storing positional information of the defective block on the SDL.
Data reading is started from the defective block in reading the data after completion of writing by repeating the above steps.
Data is written on a good block next to the defective block without writing the data on the defective block in data rewriting, after completion of writing by repeating the above steps.
If it is determined in the above step that the defective block is listed on the SDL, the defective block is skipped and the data writing/reading is conducted on a good block next to the defective block.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.